Owing to their properties, ethers of the above-mentioned type are important for a number of industrial applications. They can be used as important building blocks and starting substances for the synthesis of specialty chemicals, pharmaceuticals, natural substances, and plant protection agents.
DE-PS 28 44 635 describes a process for the preparation of 2-propylpentene-4-al-1, in which the diacetal prepared from n-valeraldehyde and 2 mol of allyl alcohol is cleaved in the presence of an acid catalyst, for example p-toluenesulfonic acid, and the intermediate ether is thermally rearranged.
U.S. Pat. No. 3,023,250 relates to the preparation of halogen-substituted, unsaturated ethers by cleavage of corresponding 1,1-di-(2-haloalkoxy)alkanes in the presence of strong mineral acids or aromatic sulfonic acids which are not volatile under the reaction conditions. A relatively low-boiling nitrogen-containing base, for example an amine, is added inside a distillation column to the reaction mixture resulting from the cleavage reaction. The addition of the nitrogen-containing base serves to neutralize acidic compounds formed in the cleavage of the halogen-containing diacetal.
L. A. Yanovskaya et al. described in Otdel. Khim. Nauk 1960, 1246 to 1253 (Chem. Abstr. 54, 24452g (1960)) a process for the preparation of unsaturated ethers, in which an appropriate aldehyde diacetal is reacted with elimination of alcohol in the presence of a catalyst composed of p-toluenesulfonic acid and quinoline to give the unsaturated ether. The yields obtained, depending on the unsaturated ether to be prepared, are between 40 and 70%.